from __future__ import annotations
from smac.facade.random_facade import RandomFacade
from smac.intensifier.hyperband import Hyperband
from smac.scenario import Scenario
__copyright__ = "Copyright 2022, automl.org"
__license__ = "3-clause BSD"
[docs]class HyperbandFacade(RandomFacade):
"""
Facade to use model-free Hyperband [LJDR18]_ for algorithm configuration.
Uses Random Aggressive Online Racing (ROAR) to compare configurations, a random
initial design and the Hyperband intensifier.
"""
[docs] @staticmethod
def get_intensifier( # type: ignore
scenario: Scenario,
*,
eta: int = 3,
n_seeds: int = 1,
instance_seed_order: str | None = "shuffle_once",
max_incumbents: int = 10,
incumbent_selection: str = "highest_observed_budget",
) -> Hyperband:
"""Returns a Hyperband intensifier instance. Budgets are supported.
eta : int, defaults to 3
Input that controls the proportion of configurations discarded in each round of Successive Halving.
n_seeds : int, defaults to 1
How many seeds to use for each instance.
instance_seed_order : str, defaults to "shuffle_once"
How to order the instance-seed pairs. Can be set to:
* None: No shuffling at all and use the instance-seed order provided by the user.
* "shuffle_once": Shuffle the instance-seed keys once and use the same order across all runs.
* "shuffle": Shuffle the instance-seed keys for each bracket individually.
incumbent_selection : str, defaults to "any_budget"
How to select the incumbent when using budgets. Can be set to:
* "any_budget": Incumbent is the best on any budget i.e., best performance regardless of budget.
* "highest_observed_budget": Incumbent is the best in the highest budget run so far.
* "highest_budget": Incumbent is selected only based on the highest budget.
max_incumbents : int, defaults to 10
How many incumbents to keep track of in the case of multi-objective.
"""
return Hyperband(
scenario=scenario,
eta=eta,
n_seeds=n_seeds,
instance_seed_order=instance_seed_order,
max_incumbents=max_incumbents,
incumbent_selection=incumbent_selection,
)